This invention pertains to disease diagnosis, prediction and treatment and, more particularly, to diagnosis, prediction and treatment of asthma, rhinitis and other inflammatory conditions associated with eosinophil accumulation in respiratory and other tissues.
Asthma is a respiratory ailment characterized by airway obstruction, inflammation and/or hyperresponsiveness. According to a 1994 survey by the U.S. Department of Health and Human Services, over 12 million Americans suffer from asthma, almost 5 million of them under the age 18. Long-term medications include corticosteroid, beta-agonists and leukotriene modifiers. For quick relief, anticholinergics, corticosteroids, and/or beta-agonists may be applied. Adverse side effects of these treatments include cough, dysphonia, candidiasis (corticosteroids), tachycardia, muscle tremor, hypokalemia, hyperglycemia (beta-agonists), liver impairment (leukotriene modifiers), drying of mouth and respiratory secretions (anticholinergics).
The standard of care for asthma dictates that treatment with the foregoing medications be a guided by disease severity of the symptoms. Since the nature of asthma is to have exacerbations and remissions, this approach undertreats patients with the potential to develop significant airway inflammation, but who at the time of pulmonary function testing are in a physiological remission. In addition, this approach can result in application of medications of greater toxicity then truly required for the condition.
One characteristic of inflammatory reactions, such as asthma and rhinitis, is the accumulation of eosinophils in the mucosal lining of the affected organs. Recruitment of eosinophils is thought to be mediated by a class of proteins known as chemokines and, particularly, by the protein eotaxin. That ligand is understood to have a high affinity for so-called CC-CKR3 receptors, which are found in large numbers on the surfaces of eosinophils.
In view of the foregoing, an object of this invention use to provide improved compounds and methods for prediction, diagnosis and treatment of disease and, more particularly, improved compounds and methods for prediction, diagnosis and treatment of asthma, rhinitis and other inflammatory conditions of respiratory and other tissues.
A further object of the invention is to provide such improved compounds and methods as permit control of such inflammatory conditions without undue risk of under- or over-treatment.
Yet another object of the invention is to provide such improved compounds and methods as permit prediction, diagnosis and treatment of such inflammatory conditions in a cost effective manner.
The foregoing objects are among those attained by the invention, which facilitates prediction, diagnosis and treatment of inflammatory conditions through exploitation of a heretofore unknown association between those conditions and a polymorphism of the eotaxin gene.
Thus, for example, the invention provides a method for diagnosis of asthma based on identification a substitution of adenine for guanine 67 base pairs following the ATG initiation codon (initiating counting at the A in that codon) of the eotaxin gene or, alternatively, based on identification of a substitution of threonine for alanine in the 23rd position of the resulting protein. The wild type (normal) eotaxin gene (i.e., without the aforementioned polymorphic substitution) is shown as SEQ ID NO: 1, below.
In a related aspect, the invention provides methods for prediction or diagnosis of asthma or other inflammatory conditions associated with tissue accumulation of eosinophils, such rhinitis and atopy, based on diagnosis of the foregoing substitutions.
Further aspects of the invention provide methods as described above in which the adenine/guanine substitution is identified by analysis of DNA or MRNA (or on other nucleic acid sequences, such as cDNA, developed therefrom) in tissue, blood or other biological samples taken from a patient or kindred thereof. Such analysis can include sequencing or probing those sequences using otherwise known techniques, as adapted to identify the aforementioned polymorphism.
In one preferred aspect of the invention, the nucleotide sequences in the samples are amplified, e.g., via polymerase chain reaction (PCR), and the amplified product is analyzed for evidence of the substitution. Such amplification can be performed, e.g., using conventional PCR or, preferably, using single-strand conformation polymorphism (SSCP) and/or amplification refractory mutation system (ARMS) techniques, though other amplification techniques known in the art can be used as well.
Further aspects of the invention provide methods as described above in which the threonine/alanine substitution is identified by contacting the biological samples with immunolabelling agents, such as monoclonal or polyclonal antibodies, raised against the variant protein (i.e., the protein resulting from the eotaxin gene with the aforementioned adenine/guanine substitution).
Still other aspects of the invention provide novel chemical compounds, notably, nucleic acid sequences for use in the diagnosis, prediction and/or treatment of the aforementioned inflammatory conditions.